1. Field of the Invention
This invention relates to valve structures, and more particularly to valve structures for use with storage devices for pressurized gases or liquids.
2. Description of Related Art
Valve assemblies are used with storage devices for storing gas or liquid under pressure. Valve assemblies regulate the flow of gas or liquid in and out of the storage device. Many valve assemblies have safety features that minimize risk to the valve assembly operator in case of damage to the assembly. FIGS. 1 and 2 show a gas cylinder 10 and a prior art valve assembly 40. Gas cylinder 10 normally stores gas under pressure. Valve assembly 40 has a canal 70 for releasing gas from cylinder 10 and for filling cylinder 10. Canal 70 is opened and closed by an angle globe valve 64. An operator operates valve 64 by turning handwheel 62.
Nozzle 50 of valve assembly 40 has protrusion 54 which defines a relatively narrow orifice 56 limiting the flow area through canal 70. Even if valve 64 is fully open, orifice 56 restricts the gas flow and thus makes the valve assembly operation safer for the operator.
Valve assembly 40 has certain shortcomings. If the relatively narrow orifice 56 gets plugged, gas cannot be released from gas cylinder 10. Furthermore, gas cylinder 10 is purged before being replaced. If orifice 56 is plugged, gas gets trapped inside cylinder 10. The trapped gas makes gas cylinder changing dangerous.
To refill gas cylinder 10, valve 64 is opened and gas is supplied under pressure from outside through canal 70. Orifice 56 restricts the gas flow and so makes filling several times longer.
Also, if valve assembly 40 is accidentally sheared off cylinder 10, the gas is released from cylinder 10 at a high rate thus placing the operator at risk.
It is desirable to provide a safe and fully functional valve assembly without the foregoing shortcomings.